珠江三角洲海平面上升对堤围防御能力的影响

珠江三角洲２０３０ 年海平面上升幅度约为３０ ｃｍ 。按此,由水力学模型计算了２４ 个站最高洪潮水位的升幅, 以５ ｃｍ 和２５ ｃｍ 等值线划分出影响很小区、影响较大区、影响最大区。由水文学方程计算了１７ 个站４ 种重现期的最高洪潮水位升幅, 得知现有堤围的防御标准在影响较大区将降低半个等级, 在影响最大区将降低一个半等级。受影响的堤围长度为２ ６０８ ｋｍ , 维护工作量为１ ７５２×１０４ｍ ３, 需投资２１ 亿元     

山东省沿海滩涂治理开发及建议

对山东省风暴潮灾害和已建的防潮工程进行初步分析;介绍山东省滩涂治理开发规划;对海堤标准、几种灾害遭遇的机率、防潮堤和防潮闸规划、必要的技术政策问题提出了自己的见解。     

武当山地块基性岩墙群地球化学研究及其大地构造意义

武当山地块基性岩墙群的地球化学特征表明,它们为具大陆拉斑玄武央珠大陆板内岸 浆侵入的产物,是古陆块裂并保存在造山带内基底岩块的重要证据,这表明南秦岭和扬子板块曾存在晋宁期固结的统一古陆块,该古陆块在新元古代早期发生了一次重要的裂解作用。     

甘肃柳园地区早二叠世正长花岗斑岩脉锆石U-Pb年代学、岩石地球化学特征——对北山造山带晚古生代构造背景的指示

甘肃北山地区位于中亚造山带中段,是诠释中亚造山带构造演化的关键区域之一,长期以来受到地质学界的广泛关注。柳园地区位于甘肃北山南带,区内脉岩发育,这些岩脉的研究可以为阐释北山造山带晚古生代构造背景提供更多证据。基于此,本文选取位于甘肃柳园地区的正长花岗斑岩脉开展了系统的锆石U-Pb-Hf同位素和全岩主量、微量元素分析。LA-ICP-MS锆石U-Pb分析显示,岩脉侵位于早二叠世（（288.5±1.4）Ma）。全岩地球化学分析显示,正长花岗斑岩脉的SiO₂和全碱质量分数较高,Fe、Mg、Ca、Al和P质量分数较低,Rb、Th、U和Pb相对富集,Ba、Nb、La、Ce、Sr和Ti等元素相对亏损,Eu负异常显著,具有较高的Rb/Sr值和较低的K/Rb值及锆石饱和温度（730~844℃,集中于740℃左右）,显示该岩脉为高钾钙碱性高分异I型花岗岩,并具有俯冲带岩浆活动的地球化学特征。正长花岗斑岩脉具有较低的Zr/Hf值（18.42~28.01,平均值为22.37）和Th/U值（3.82~7.99,平均值为5.34）,与平均地壳组分接近,锆石ε_Hf（t）值为2.94~9.66,平均值为5.72,T_DM2值为955~611 Ma,指示源区主体为新元古代地壳的部分熔融,并存在幔源物质加入。根据构造判别图解并结合前人关于二叠纪区域构造变形、盆地沉积物源、岩浆演化等方面的研究结果,笔者认为该正长花岗斑岩脉形成于俯冲作用过程中的局部伸展环境,并认为北山地区增生造山事件至少持续到早二叠世。     

Bed morphology and grain size characteristics around a spur dyke

This paper presents an experimental study on the local bed morphology and grain size characteristics around an impermeable spur dyke.A series of experiments are conducted with different types of sedime...     

Decoding Neoarchaean to Palaeoproterozoic tectonothermal events in the Rangnim Massif,North Korea: regional correlation and broader implications

Any knowledge about Archaean to Palaeoproterozoic magmatic and metamorphic events in North Korea has the potential to make a significant difference to our understanding of the early tectonic configuration and evolution of East Asia. This zircon U–Pb dating and Hf isotopic study documents multiple Neoarchaean to Palaeoproterozoic tectonothermal events from the meta-igneous complex in the Machollyong ‘Group’ of the Rangnim Massif. Two tonalitic-trondjemitic gneiss samples record a crystallization age of meta-igneous protoliths at ca. 2.56 Ga and multiple migmatization and metamorphism from 2.52 to 1.85 Ga. A meta-dolerite sample yields a magmatic emplacement age of ca. 1.83 Ga. In situ zircon Hf isotopic data indicate that most zircons from the gneiss samples have ε_Hf(t) values from –16.9 to + 3.1 and crustal model ages from 2.84 to 3.73 Ga, whereas magmatic zircons from the meta-dolerite dike record ε_Hf(t) values from –5.2 to + 5.2 and model ages of 2.05–2.44 Ga. The first-recognized Neoarchaean tonalitic-trondjemitic migmatite complex in the Rangnim Massif, together with previously identified tonalitic-trondhjemitic-granodioritic (TTG) rocks in the Rimjingang Belt and the coeval counterparts in western Gyeonggi massif, represents the oldest crustal nuclei in the Korean Peninsula. The multiple tectonothermal events in this study present reliable evidence not only for attesting to consanguinity of the basement between the Korean Peninsula and the North China Craton but also for defining the influence scope of the late Palaeoproterozoic orogeny in the Korean Peninsula.     

Analysis of patterns of vertical and temporal distribution of phytoplankton using multifactorial analysis: Acidic Lake Caviahue, Patagonia, Argentina

Most existing studies on the algal communities of acid lakes are based on environments that have been caused by anthropogenic disturbances. Such lakes have a different origin compared to the natural acidic lakes and could be expected to differ also in the mechanisms controlling phytoplankton and trophic status. Planktonic community in Lake Caviahue is somewhat diverse in spite of the low pH of the water. Algae have a distinctive vertical distribution: the values of phytoplankton biomass remain constant throughout the water column and at times were highest in the upper end of the hypolimnion, forming a maximum or a layer of chlorophyll a at depth. The goal of this work was to investigate the factors influencing the seasonal and vertical distribution of phytoplankton. The lake was sampled between the years 2004 and 2006. Physical, chemical and biological parameters at different depths throughout the water column were determined. The interrelationships between environmental variables at different sampling dates were analyzed using an integration of multivariate matrices, multiple factor analysis, to analyze any joint partnerships in the samples. We found that phytoplankton biomass is dominated by Keratococcus rhaphidioides. With regard to zooplankton, we found a single species of rotifers (Philodina sp.). The two arms of the lake and the depths have different behaviours showing differences in the arms' conductivity, dissolved oxygen and pH. The more superficial layers were characterized by high values of phytoplankton and zooplankton biomass, organic and inorganic carbon, dissolved oxygen and pH. The deeper layers showed high values of chlorophyll a, ammonium and phosphorus (dissolved and particulate). From the multivariate analysis the relationships of the each algal species with pH, as a possible indicator of the degree of “acidophilia”, could be extracted.     

Discovery of a Miocene Mafic Dyke from the Western Hills of Beijing and its Geological Implications

Abstract: The present study is the first report of a Miocene mafic dyke from the Dahuichang, in the Western Hills of Beijing. The dyke cuts the fossil-dated Changxindian Formation of Eocene sequences and yields K-Ar ages of 14–15?Ma. The dyke is fine-grained diabase and has 49.84%–50.81% SiO2 and 3.56–3.97% Na2O+K2O, high TiO2 (1.65%–1.93%) and MgO (7.36%–9.85%), and low K2O (<1.22%) contents, with Na2O>K2O and slightly varied magnesium numbers (Mg#=55.54–62.74). In trace elements geochemistry, the dyke is very similar to the Miocene basalts from Jining and Hanuoba. The enrichment of light rare earth elements ([La/Yb]N=5.03–6.12) and large ion lithophile elements (LILEs?), no negative Eu anomalies, relatively high Cr (265–326 ppm) and Ni (155–262 ppm), and almost constant V concentrations (194–213 ppm) reveal that the composition close to the primary basaltic magma from ?an enriched-mantle source, with little crustal contamination and fractional crystallization. The basaltic magma was possibly derived from the upwelling asthenosphere mantle beneath eastern China during the Miocene lithospheric thinning.     

新疆青河县野马泉金矿床地质及地球化学特征

野马泉金矿床位于准噶尔微板块东段,东准噶尔晚古生代陆缘盆地的南部,喀斯开尔索克坎大断裂西侧,哈萨坟复背斜轴部;矿体呈脉状主要赋存于蚀变闪长玢岩脉中及其内、外接触带。蚀变闪长玢岩脉的围岩为志留系库布苏群下亚群粉砂质板岩、千枚岩化粉砂岩;矿床成因类型为次火山热液-变质热液叠加型。